This series continues the theme of Factors causing dreams.
When we sleep, we are still receptive to external stimuli like sounds, our skin’s temperature sensations, and smell. We also feel internal organs like the stomach, when we receive nerve signals that say the stomach is growling for food. After processing these signals, the brain creates dream images tat are related to these stimuli. For example, when the stomach is hungry, we see dream imagery of food and dream of eating.
A stimulus enters a dream as a related image.